deletions | additions       diff --git a/Casida, Tamm-Dancoff, and excited-state forces.tex b/Casida, Tamm-Dancoff, and excited-state forces.tex  index 0a041f0..adec593 100644  --- a/Casida, Tamm-Dancoff, and excited-state forces.tex  +++ b/Casida, Tamm-Dancoff, and excited-state forces.tex 
...
\end{align}  and the absorption cross-section is  \begin{align}  \sigma_{ij} \left( \omega \right) = \frac{4 \pi \omega}{c} \tilde{\alpha} \ \mathcal{I} \mathrm{Im}  \alpha_{ij} \left( \omega \right)\ , \end{align}  where $\tilde{\alpha}$ is the fine-structure constant.  %and the oscillator strengths are